CB 750 to CB450 Triple Tree, change over problems, HELP!

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SimonJ18
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CB 750 to CB450 Triple Tree, change over problems, HELP!

Post by SimonJ18 » Tue May 16, 2006 7:39 pm

After reading these posts....

http://www.choppersaustralia.com/forum/ ... .php?t=264
http://www.choppersaustralia.com/forum/ ... .php?t=262

I thought i'd try to do the CB450 Triple tree swap on my CB750 Chop, the CB450 trees are a bit cleaner looking and have the bolt in risers which are mounted with bushes which would dampen out some of the vibration thru the bars etc.. :)

I am trying this and i am having problems!!

First of all, Are these CB450 Trees??

Image

I bought these off of E-bay for $10, They are from a CB450.. not sure on the year but it was a pre disc brake bike, I have found that the fork holes are about 10mm closer together than the CB750 i have, is this the reason the r narrower? Do the Drum brake fronts run a narrower stance on the forks?



Here is a picture of the top trees, you can see the difference in fork sleeve spacing, i think it is about 10mm difference... my verniers didnt open wide enough. 450 trees on top, 750 trees on bottom.

Image

Next Dilema.....

Ok, so the forks are only 10mm out.... My biggest woes are the neck stem lengths....

Image

So swap it over with your CB750 neck stem you say?..... Sure, i would, if it wasnt welded??

Image

Is this normal?? I thought they were bolted and i could change out the neck stem??

Can anyone shed some light on this?? I am bloody confused! :evil: And annoyed, i spent the morning strippin the paint off of these ready to polish and clear coat :(
Last edited by SimonJ18 on Wed May 17, 2006 2:04 am, edited 1 time in total.

Cromag
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Post by Cromag » Tue May 16, 2006 11:20 pm

This is why its called Chopping........get the grinder out, MUUuuuHHHAAAAhaaaaaaar, turn the bottom stem upside down locate the weld holdin the dirty blighter together and start at it. when you can see a seam running all the way around the base of the stem, take it to your vice open the jaws a little wider with the stem pointed to the floor, and belt the stem ouyt with a drift. Do the same to the other one............damn you measured them first to see if the same dia didnt you?......then swap the stems over if right dia, and weld around the base (the underside) until fixed, bolt up cause it all should go well.

Ive ridden many miles on stems like this and except for the fact it ruins the chrome its all good. (Just did this job only 4wks ago, happy with result just need a k series top yoke now.) Good luck.

SimonJ18
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Choppin

Post by SimonJ18 » Tue May 16, 2006 11:35 pm

Cheers Fella!! i just hope the forks fit!! i didnt realise that the CB750 neck stem were welded in! Tomorrow i will try to slip the forks into the trees, if this works... i will grab another stem and bottom triple clamp from the wreckers and cut it out and weld it in :) Yes the stems are the same diameter and the bearings fit too! Wow the 450's have a lil key to lock the neck up :)

The only thing that still bothers me is the spacing for the forks, but stuff it i will go ahead, just hope it doesnt bring the bottom of the forks in too snug for the disk brake etc.....

Thanks again, will post back on results tomorrow 8)

Cromag
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Location: NSW

Post by Cromag » Wed May 17, 2006 12:25 pm

Aaahhhhh Now I see said the blind man, Why not extend the stem by cutting in half adding required amount and welding back together, slugged of course. Id prefer to swap the whole stem myself.

Also youve got 10mm to sought out. maybe just winding the nut side of your axel in will be enough to get the bottom right, ........possibly you may have to take 5mm per side of the hub where the disks sit, if you do need to do this i have a bare front hub you can have for cost of postage, that way you save the front wheel youve got.

Possibly look into other disks without as much rise in them, while your at the wreckers. Good luck.

SimonJ18
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Post by SimonJ18 » Wed May 17, 2006 12:56 pm

I should be taking delivery of my bike lift tomorrow or friday, so i will tackle the job then... any one got a spare cb750K series bottom tripleclamp and neck stem section laying around??

Chopper_T
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Location: Mudtapilly, Queensland

Post by Chopper_T » Sat Jun 03, 2006 9:58 pm

Looks like a cool conversion. I have been contemplating a trail-bike front end for my chop for a while. I like the idea of a clean looking set of trees with a bit of width. My only concern is the travel in off-road forks and bottoming out the chop on bumpy roads.

I was reading before about someone using road-trail forks. I shoulda asked how they went for strength with a high powered 4 pushin on 'em. Lookin' at your project, you might be able to shed some light on it for me.

I'd like to see a pic when you got the front end together, to see how it all looks.

SimonJ18
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Post by SimonJ18 » Sun Jun 04, 2006 1:34 am

Hi Chopper T, i wish i could show you a pic but unfortunately that conversion is in the trash.... The 750/4 forks measure 35 odd mm's and the tree's accept 32-33 no biggy tho they can be honed out. Next issue is the neck rod, no probs tho we got a spare 750/4 neck rod, but the biggest problem is the width the trees set the forks, and the 450/4 trees bring the forks in narrower which is no good for us because we need all the width we can get as we are running a twin disc brake front (early style). I still want the bolt in riser option as i want to run some that are pull backs and about 4-6in long... I plan to fill the underside of a 750/4 top tree with aluminium filler rod then mill the fork clamp bottoms off the top of the tree, mark and drill holes for my risers and waa lah! Sounds easy, kinda :shock: will give it a go in a couple of weeks and let you know the results :)

Cromag
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Post by Cromag » Sun Jun 04, 2006 9:42 am

Could always go Dog Bones SJ18

SimonJ18
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Location: Adelaide, Australia...
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Post by SimonJ18 » Sun Jun 04, 2006 11:40 am

Yeah i know cromag, but i dont like em... i dunno why maybe i am bein fussy but i just want to keep the looks real clean.

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